1. Field of the Invention
The present invention relates to a hollow golf club head called a metal wood which is made of a metallic material.
2. Description of the Background Art
Golf clubs have achieved remarkable development as represented by enlargement of the head, extension of the shaft, and use of metallic materials with a high strength. This development effort has the target of allowing golf balls to be hit far in the right direction and increasing the meet rate, the rate at which the ball is hit by a sweet spot on the golf club.
Particularly, development of titanium alloys which are light (specific gravity: 4.5-5.0) and strong has allowed a significant increase in the head size and shaft length, enabling golf clubs to approach the above target.
However, development in this line approaches a limit. Specifically, a large moment of inertia and an increased meet rate can be achieved by a large golf club head, but enlarging the size of the golf club head increases its weight. The weight of the golf club heads currently manufactured is close to a limit. For instance, the weight allowed for a golf club with a shaft length of 45-46 inches is 190-200 g at most.
Although various titanium alloys (from 6-4 Ti to xcex2-type Ti) are ideal metallic materials for a golf club head in terms of their strength, corrosion resistance, and processability, titanium alloys are expensive materials.
An object of the present invention is therefore to provide a golf club head which can be enlarged, can exhibit a large moment of inertia and an increased meet rate, has design freedom and excellent processability, and yet can be manufactured at a low cost.
The above object can be achieved in the present invention by a hollow golf club head made of one or more metallic materials selected from the group consisting of martensite deposition hardening-type stainless steel, maraging steel, and maraging stainless steel.
In a preferred embodiment of the present invention, the above hollow golf club head comprised a main head body formed by press-forming from a casting material or sheet material, a face part formed by press-forming or forging, and a sole or crown part formed by press-forming from a casting material or sheet material, all of which are joined by welding or brazing.
The above object can be further achieved in the present invention by a hollow golf club head made of one or more metallic materials having a specific gravity of 7.70 or more, the head having a volume of 280-320 cc and a weight of 180-205 g.
Other features, objects and advantages of the present invention will become apparent from the following description of the preferred embodiments with reference to the drawings.